The scroll saw blade of a conventional scroll saw may displace and deviate in the forward and backward direction when in use, so it is not easy for the user to control the position of the scroll saw blade exactly. Therefore, an improved scroll saw is developed as disclosed in U.S. Pat. No. 5,390,577 or as disclosed in U.S. Patent Application Publication No. 20160045963 filed by the inventor of the present invention. The scroll saw has a worktable. The worktable is provided with a pair of transmission shafts respectively disposed above and below the worktable. One end of each transmission shaft is connected to a drive unit, and the other end of each transmission shaft is provided with a clamping unit. The clamping unit has a slide seat. The slide seat is provided with a slider. The scroll saw further includes a scroll saw blade. Two ends of the scroll saw blade are connected to the sliders of the two clamping units, respectively. The drive unit drives the transmission shafts to rotate simultaneously, and the transmission shafts respectively bring the sliders of the clamping units to slide straight up and down relative to the worktable so as to drive the scroll saw blade to perform linear sawing operation straight up and down, such that the user can control the position of the scroll saw blade for precise sawing operation.
However, the inventor of the present invention finds that in actual operation of the above-mentioned scroll saw, the drive unit, namely, the motor gear assembly as disclosed in the U.S. Pat. No. 5,390,577 or the motor belt assembly as disclosed in U.S. Patent Application Publication No. 20160045963, due to a backlash between the gears or an elastic tension of the belt itself, may generate a deviation when the transmission shafts are running, and the transmission shafts do not run in parallel, resulting in a violent vibration during the operation of the scroll saw blade. The vibration not only accompanies a loud noise but also seriously interferes with the user to operate the scroll saw, which also causes a vibration of the scroll saw easily. In addition, the sliders of the clamping units are driven by the transmission shafts to slide back and forth on the slide seats at a high speed to generate a lot of friction heat, so the scroll saw cannot be used for a long time. As a result, the scroll saw cannot be put into mass production for industrial use.
Accordingly, the inventor of the present invention has devoted himself based on his many years of practical experiences to solve these problems.